The working hypothesis of this proposal is that enamel proteins play a central role in the process of amelogenesis and that determination of the structure and expression of these proteins is essential to an understanding of that role. With presently available techniques, solubilized enamel proteins can be divided into two classes of proteins, amelogenins and enamelins, containing a total of 15 to 25 components. It is not known how many of these components represent the products of individual genes, whether the multiple components are derived from the physiologic breakdown of a limited number of proteins or are artefactually produced. The overall objective of this proposal is to characterize the structure and expression of the enamelin protein, tuftelin, and to relate the structure of the protein to its potential function. To achieve this objective, 4 Aims are proposed: (1) To complete the characterization of the bovine tuftelin gene. (2) To identify the functional elements of the tuftelin gene promoter, the site(s) of transcription initiation and whether the primary transcript is alternatively spliced. (3) To determine the temporal and spatial expression of tuftelin-related polypeptides in the developing bovine enamel organ. (4) To investigate potential structure/function relationships of tuftelin using recombinantly expressed protein. Identification of functionally significant promoter elements is essential to an understanding of control of expression of the tuftelin gene, and it is important to determine whether alternative splicing contributes to the observed hetgerogeneity of enamelins. Because of the difficulty involved in purifying native tuftelin, recombinant synthesis is the method of choice for obtaining it in quantity. The proposed studies will use state of the art molecular and cellular biology, immunologic and physical techniques. The information gained from these studies may ultimately (i) lead to better understanding of the functions of enamel proteins, (ii) lead to an explanation of some genetic defects affecting the enamel matrix, (iii) lead to the development of more effective and biologically compatible restorative materials.